+ /**
+ * Adds a new flag at a specified time.
+ */
+ void add_flag(double time);
+
+ /**
+ * Removes a flag from the list.
+ */
+ void remove_flag(std::shared_ptr<Flag> flag);
+
+ /**
+ * Gets the list of flags.
+ */
+ std::vector< std::shared_ptr<Flag> > flags() const;
+